My rig:
16Gig 1333 Ram
Game is running off a Black Caviar 1tb drive
i2600k @ 4.5ghz
EVGA GTX570
On-board Sound (Audigy no longer fits)
... BUT at 1920x1080 I get studdering, and it's annoying as hell watching a character run by me, as if it's in a flip book, BUT fans in the background rotating perfectly normal.
SO I run the game at 1600x1050 or whatever the next resolution down from 1080 is.
Looks identical to me, and runs exactly same frame-rates, but no studdering.
I use RIVA TUNERS "Direct3D Overrider" and MSI's AFTERBURNER with core set to: 1025 (1.025) and clock 800mhz all with custom fan profile - louder. but 80° down to 60°c.
So, i2600k, GTX570, game runs perfectly smooth and when I record in FRAPS I go down to 35fps which isn't noticeable. (caught ceph overlord cheating on tape bwahahaha)
****
Just remebered, I read some-where that shadows on "Extreme" vs. "Ultra" removes the framedrop when up close to explosions etc... so that's the only thing not on ULTRA.